Apparatus for controlling fuel feed in furnaces



Dec. 8, 1931. E. RoukA APPARATUS FOR CONTROLLING FUEL FEED IN FURNACES Filed March 18, 1930 ATTORNEYS Patented Dec. 8, 1931 ERICK ROUKA, F BLANSKO, CZEGHOSLOVAKIA APPARATUS FOR CONTROLLING FUEL FEED IN FURNAES Application filed March 18, 1930, Serial No. 436,664, and in Czechoslovakia March 30, 1929.

This invention relates in general to apparatus for controlling the feeding of fuel to furnaces, and more particularly the invention is directed to the control of mechanical fuel feeding grate mechanism or the rate of supply of fuel in, for example traveling or chain grate furnaces.

Known apparatus of this general character includes means sensitive to temperature of the fuel bed at the fire ,end, or fire line, or the end of the mass of live coals, at the discharge end of the grate, which controls means for actuating or moving the grate so that feed of fuel is started and stopped upon a fall and a rise respectively of the temperature at the fire end on the grate.

One object of my invention is to provide in apparatus of this general character novel and improved means for transmitting radi 0 ant heat from the fuel fed at the fire line on the grate to said temperature sensitive means including a hollow or tubular member in which is a fluid, such as air, heated by the fire, which fluid flows from said hollow memher to the temperature sensitive means, the flow of fluid preferably being variable with the temperature of the fuel bed so that the heat from the fuel bed is tempered to maintain an efficient supply of fuel. In other words, my invention aims to prevent the temperature of the fluid becoming so high upon an increase in temperature 'at the fuel line, as to maintain said temperature sensitive means in position to prevent fuel feeding so long as to allow the fuel on the grate to be too far consumed before more fuel is supplied.

Another object is to provide such apparatus wherein the flow of fluid to said temperature sensitive means shall be varied by the draft in the furnace. This is an important object since without my invention, upon an increase in draft the temperature at the fire line would increase so that the fire line might recede too far and the fire become too short or the fuel too far consumed, before the temperature affecting the temperature sensitive means would fall sufficiently to start the feeding of more fuel; while with my invention, 60 upon an increase indraft the flow of fluid through the hollow member will correspondingly increase so that the fluid will not become so hot and the temperature sensitive means will be actuated to maintain the position of the fire line steady through eflicient control of the grate mechanism.

Other objects are to provide fuel feed control' apparatus of the character described wherein said hollow fluid conducting member shall be connected at one end to the ash pit of the furnace and at the other end to theflue, whereby the draft maintains a circulation of air through said member from the ash pit, over the the to the temperature sensitive means; to provide in such apparatus means for further varying or controlling the flow of fluid through said hollow member, said means preferably being actuated in accordance with the draft controlling device; and to obtain other advantages and results as will be brought out by the following description.

Referring to the accompanying drawings in which corresponding parts are designated by the same reference characters throughout the several views Figure 1 is a fragmentary'schematic side elevation of a chain grate mechanism for a furnace showing a portion of my invention applied thereto, and

Figure 2-is a transverse vertical sectional view on the line 2-2 of Figure 1 with a schematic illustration of my fuel feed controlling apparatus.

For the purpose of illustrating the principles of my invention I have shown it in con nection with a furnace of known construction including a fire box 1 having a. known type of traveling or chain grate 2 which is actuated through worm and worm wheel gearing 3 by an electric motor l which is connected to a source of electricityby line wires 5 through a switch 6 actuated into closed position by an electromagnet 7 and into open position by a spring 8. The fuel is supplied at one end of the grate by known means such as a hopper (not shown) and the grate travels in the direction of the arrows, the fuel being discharged upon the grate and the ashes being discharged by action of gravity into an ash pit 9 at the end of the grate opposite the fuel supply. The fire line, fire end, or the end of the mass of live coals upon the grate, is designated 10, and the position of this fire line varies from time to time moving toward the fuel supply end of the grate as the fuel is consumed, and toward the discharge or ash pit end of the grate as the grate is actuated to supply additional fuel. Any suitable means may be provided for producing a draft through the hire box; for example the ash pit may have the usual door 11, and the fire box above the grate 2 may be connected to a flue 12 which is in turn connected to a chimney or stack 13. The draft may be controlled in any suitable manner, as by a damper 14 in the fine 12; and either natural, forced or induced draft may be utilized.

Above the discharge end of the grate at a position with respect thereto corresponding to the position at which it is desired to main tain the fire line, is arranged a hollow or tubular member 15 which has on the side thereof next to the fire a plurality of metal strips or ribs 16 for conducting heat radiated from the fire into the hollow member 15. A current of fluid, for example, air, is-

caused to flow through this hollow member 15 so that the air will become heated from the fire, and this heated air is then brought into contact with a heat sensitive means which may comprise a thermostat consistin of two strips 17 and 18 one of which is bimetallic, and both of which have one end fast secured at 19 to a casing 20 which is connected to and communicates with one end of a hollow member 15. These strips 17 and 18 have cooperating contact points 21 and 22 and are connected in circuit with the line 5 through the wires 24 and 25 so as to control the electromagnet 7.

Any suitable means may be utilized for producing the flow of fluid or air through the hollow member 15, but preferably, said hollow member is connected to the draft producing means for the furnace so that the flow of air through the hollow member varies in accordance with the draft; To this end, one end of the member 15 maybe connected by a pipe 26 to the ash pit 9, while the casing 20 is connected by a pipe 27 to the flue 12 between the fire box and the damper 14.

In operation of the apparatus, the contacts 21 and 22 of the thermostat 17, 18 are normally separated so as to open the circuit through the electromagnet 7; and air flows through the hollow member 15, heated by the radiant heat from the fire line in the fuel bed and conducted in contact with the thermostat 17, 18. Obviously the temperature of the air will vary a cording to the position at the fire line 10. When the fire line recedes to the left of the figure toward the supply end of the grate, the temperature of the air in the hollow member 15 falls so that the thermostat 17, 18 is actuated to close the contacts 21, 22. This energizes the electromagnet 7 which closes the switch 6 and starts the motor 4 so vas to actuate the grate 2 in the direction of the. arrow, supply new fuel and move the tire line toward the right of Figure 1. After a time the temperature of the air in the hollow member 15 rises due to the hotter lire directly beneath it resulting from movement of the tire line, whereupon the thermostat 17, 18 is actuated to separate the contacts 21, 22 and throw the motor 4 out of operation so as to stop movement of the grate and feeding of fuel.

It will be clear that upon an increase in the draft, the temperature at the fire line in the fuel bed will rise so as to tend to maintain the thermostat 17, 18 in the position to prevent actuation of the grate for a long period of time, but this tendency is overcome with my invention by the corresponding increase in the flow of air through the hollow member 15 so that the temperature of the air is kept lower than the temperature at the lire line; in other words, the air is tempered. On the other hand, if the draft is out oil, or the fire damped, the flow of air through the hollow member 15 is correspondingly decreased. Accordingly it will be observed that the flow of air through the hollow member 15 is varied in accordance with the load on the furnace and with the consequent variations in temperature at the fire line in the-fuel bed, automatically by a variation of the draft which is regulated in accordance with the load variations. In some instances it may be desirable to provide additional means for varying the flow of air through the hollow member 15, and such means may consist of the dampers 28 and 29, the first of which is arranged in the pipe 27 between the flue 12 and the casing 20, while the latter is arranged between the atmosphere and the pipe 27. These dampers are preferably operated together and in accordance with the operation of the damper 14, by any suitable .means known in the art, either manual or automatic. A hand or automatically controlled damper device is designated by the reference character 30 while its connections with the dampers 29, 28 and 14 are designated 31, and 33 respectively. With such apparatus it is possible to vary the flow of air through the hollow member 15 to establish a particular relation between such flow and the furnace draft, or for any other desired purpose.

' It is also possible to use in connection with this apparatus means for preventing hunting action such as described and claimed in my copending application Serial No. 436,665, filed March 18, 1930. This means may comprise generally an electric heater 34 adjacent the thermostat 17, 18 and conof illustrating the principles of the inven nected in circuit with the motor 4 suitably controlled by the switch 6; This heater supplements the heating action of the air in the member 15 upon the thermostat, or accelerates the action of the thermostat so as to prevent the supply of excessive amounts of fuel at long intervals, and insure regular and efiicient fuel supply.

While I have shown and described my invention schematically as embodied in certain details of construction it should be understood that this is primarily for the purpose tion and that the invention may be embodied in various details of construction without departing from the spirit or scope of the invention.

Having thus described my invention, what I claim is: V

1. The combination with a furnace having a fire box, a grate mechanism for feeding fuel, and a draft conduit, of means for actuating said grate mechanism, means for connecting and disconnecting said actuating means to and from a source of power, a hollow member disposed above the fire line of the fuel bed and connected to said draft conduit so as to have air flowing therethrough, the flow of which varies in accordance wlth the furnace draft, and a temperature sensitive means actuated bythe temperature of the air after it has been heated in said hollow member for actuating said controlling means.

2. The combination with a furnace having I a fire box, a grate mechanism for feeding fuel, a draft conduit, and means for varying the draft, of means for actuating said grate mechanism, means for connecting and disconnecting said actuating means to and from a source of power, a hollow member dis sed above the fire line of thefuel bed an connected to said draft conduit so as to have a current of air flowing therethrough, means for controlling the flow of air through said hollow member actuated in accordance with the means for varying the draft, and temperature sensitive means actuated by said temperature of the air after it has been heated in said hollow member for actuating said controlling means.

ERICH ROUCKA. 

